Contact air cooling system



- Dec. 8, 1959 Filed Oct. 21. 1957 O. JENSEN CONTACT AIR COOLING SYSTEM2 Sheets-Sheet 1 INVENTOR. flrra JE/VJE/V Dec. 8, 1959 o. JENSEN2,916,563-

CONTACT AIR COOLING SYSTEM BY W 7; 4

Jrraovrxr United States Patent CONTACT AIR COOLING SYSTEM Otto Jensen,Malvern, Pa., assignor 'to I-T-E Circuit Breaker Company, Philadelphia,Pa., a corporation of Pennsylvania Application October 21, 1957, SerialNo. 691,224 7 Claims. (Cl. 200-19) My invention relates to a novel meansfor cooling a pair of cooperable contacts as well as removing foreignparticles from the cont-acting area, and more specifically relates to acooling and cleaning system for contacts of the repetitively operatedtype, such as mechanical rectifier contacts.

Mechanical rectifiers and the contacts therefor are completely describedin my copending applications Serial No. 307,067 filed August 29, 1952,now Patent No. 2,798,909, and Serial No. 558,350, filed January 10,1956, now Patent No. 2,851,562 and assigned to the assignee of theinstant invention.

As may be seen from reference to these copending applications, amechanical rectifier, taken by way of example, utilizes a pair ofcooperable contacts connected between an A.-C. source. and a D.- C.load. The contact is synchronously operated so that when the voltage ofthe A.-C. source is positive, the contact is closed, and this voltage isapplied to the D.-C. load. When, however, the voltage of the A.-C.source reverses, the contact is open and the D.-C. load is disconnectedfrom the A.-C. source. By synchronously operating the contact in thismanner with respect to the frequency of the A.-C. source, the D.-C. loadwill have impressed thereon a unidirectional voltage of somepredetermined average value.

Several serious problems are present in the utilization of this type ofcontact, primarily due to the relatively high contact currents which insome cases may be as high as 5,000 amperes, and also due to the factthat the contacts must operate sixty times every second, or 216,000times every hour when rectifying a sixty cycle A.-C. source.

These problems primarily are excessive heat generation within thecontact due to resistive heating of the contact material and resistiveheating due to the contact resistance, and foreign material such as dustor specks of contact material which appear within the area of contactengagement. The latter noted problem of foreign material will, ofcourse, increase the contact resistance so as to further increase theheat generated at the contact, but also may serve to initiate a smallare immediately prior to contact closure, thus causing a weld which willbe torn apart when the contact is open. Since this process iscumulative, after a relatively few operations the contact surfaces maybe seriously damaged, and lead to a backfire or a high power are throughthe contact when the contact is opened. In a similar manner, a foreignparticle may cause an arc to be drawn during contact opening.

The principal object of my invention is to provide a novel means forboth cooling the contacts and dislodging foreign matter which appearswithin the contacting area.

In a preferred embodiment of my invention where a movable contactcooperates with a pair of relatively stationary contacts in a bridgingarrangement, I drill a hole through the center of the movable contact.The

movable contact, which may have a biasing spring placed respect to thestationary contacts, then has a fluid conduit introduced through theaperture or hole in the contact and runs along the central axis of thespring to some outer source of high pressure fluid such as air.

The fluid conduit is terminated at a point substantially adjacent to thecontact engaging area and within a depression in the head of anoperating pushrod which moves the movable contact against the force ofthe biasing spring and out of engagement with the cooperating stationarycontacts when disengagement is required.

This depression, in conjunction with other fluid passages in the pushrodhead, then serves to deflect air or fluid brought through the fluidconduit into the contacting area.

By way of example, the portion of the pushrod head which engages themovable contact may be fluted whereby air rushes from the fluid conduitinto the pushrod depression and then upwardly between the walls of thedepression and the outer walls of the conduit through the flutedsegments of the pushrod head and into the area formed by thedisengagement of the cooperating con-- tacts.

It is to be noted that this air flow in the said area Willi berelatively turbulent so that the cooling eflect of the; air isamplified. Furthermore, this air will pick up any foreign particleswithin the area and blow them out of" the contact area.

Furthermore, the cooling effect may proceed even-r when the pushrod isremoved from the movable con:- tact and the contacts are engaged, forwith this condition air will be deflected by the pushrod depression andvmay escape through a passage formed by the outer por-- tion of thepushrod head and the outer portion of the engaged movable and stationarycontacts. Hence, the cooling effect may proceed even though thecooperating contacts are engaged and the area formed by contactdisengagement is not present.

Accordingly, an important object of my invention is to provide a novelcooling system for contacts wherein a fluid conduit is connected to thearea of contact engagement when the cooperating contacts are disengaged.

Another object of my invention is to provide a novel cooling means formechanical rectifier contacts wherein the top of the pushrod head servesto form a passage for deflection of air from a fluid conduit whichpasses through an aperture in the movable contact into the area createdby contact disengagement.

Another object of my invention is to provide a novel cooling system forcontacts wherein cooling and cleaning proceeds when the contact is in anopen position.

These and other objects of my invention will become apparent from thefollowing description when taken in conjunction with the drawings, inwhich:

Figure 1 shows an exploded perspective view of the preferred embodimentof my novel invention taken in conjunction with a mechanical rectifiercontact.

Figure 2 is a side view of one possible modification of the pushrod headof Figure 1.

Figure 3 is a cross sectional view of the pushrod head of Figure 2 when,taken across lines 33.

Figure 4 is an assembled cross-sectional view of the embodiment ofFigure 1 when the cooperating contacts are in their engaged position.

Figure 5 is similar to Figure 4 with the cooperating contacts in adisengaged position.

Figure 6 is a schematic circuit diagram of a threephase half-wavemechanical rectifier circuit wherein the contacts are adapted inaccordance with my novel invention.

Referring now to Figures 1, 4 and 5 which show a typical mechanicalrectifier contact of the type set forth inmy above noted copendingapplications Serial No. 307,067 filed August 29, 1952, now Patent No.2,798,909 and Serial No. 558,350 filed January 10, 1956, now Patent No.2,851,562, a pair of stationary contacts 10 and 12 are clamped by aclamping means (not shown) to an A.-C. bus 14 and a D.-C. bus 16 whichbuses are subsequently connectable to an A.-C. source and DC. loadrespectively.

In order to connect the A.-C. source and DC. load (not shown), when thepolarity of the A.-C. source is of a desired value a movable contact 18is brought into bridging engagement-with respect to stationary contacts10 and 12 in a manner to be described hereinafter.

Movable bridging contact 18 has an aperture '20 therein which passes afluid conduit 22, as will be more fully described hereinafter.

Movable contact 18 is normally biased into contact engagement withrespect to stationary contacts 10 and 12 by means of biasing spring 24which bears against a relatively stationary spring support member 26. Inorder to achieve contact disengagement a pushrod device 28, which isoperated from a motor 30 in such a manner as to impart linear motion asindicated by the arrow 32 to the pushrod 28, is in a lower position whendisengaged with respect to the movable contact 18. When, however, themotor 30, operating through an operating linkage of the type which iscompletely described in my above noted copending application Serial No.307,067 filed August 29, 1952, now Patent No. 2,798,909 drives pushrod28 upwardly, the top of pushrod 28 or the pushrod head is brought intoengagement with the underside of contact 18, and moves the contact 18 toa disengaged position against the force of biasing spring 24-. (SeeFigure 5.)

Figures 1, 4 and further show the top of the pushrod 28 as having adepression 34 therein which depression receives the open end of fluidconduit 22. The top of pushrod head 28 is fluted, as seen by flutedportion 36, so that even through the top portion 36 of pushrod head 28engages the under side of contact 18, it will be in a non-airtightmanner.

Clearly, the opposite end of fluid conduit 22 will have a source of highpressure fluid connected thereto so that this fluid will move throughconduit 22 to emerge within the depression 34 of the pushrod 28 at apoint which is substantially intermediate an area created by themovement of the cooperating contacts to a disengaged position.

The cooling and cleaning effect of my novel system may be bestunderstood by reference to Figure 5 where the air flow through conduit22 is indicated by the arrows. Thus, the air flow proceeds down theconduit 22 and into depression 34 where it is deflected by the bottom ofthe depression and then flows upwardly through a passage defined by theinner walls of depression 34 and the outer surface of conduit 22. Thefluid then reaches the fluted top portion 36 of pushrod 28, which flutedportion defines passages leading from the depression 34 to the areaformed between the movable contact 18 and the stationary contacts and 12when the movable contact is disengaged.

Thus, the relatively high pressure fluid emerges through the flutedsection 36 into this area in a turbulent manner, as indicated by thearrows in this area, so that both cooling of the contact surfaces ofcontacts 10, 12 and 18 and removal of foreign particles in this area isachieved.

It is to be noted that in the case of Figure 4 where the movable contact18 is closed an air passage is still formed between depression 34 and anarea external of the stationary contacts 10 and 12 through which a fluidcan pass. That is to say, fluid may pass through the .fluted section 36and then between the outer portion of the. top of the pushrod 28 and theinner surface of stationary contacts 10 and 12 whereby cooling of thisportion of the stationary contacts is achieved.' Further air may escape4 in a direction parallel to the adjacent surfaces of the stationarycontacts 10 and 12 and against the lower surface of the movable contact18 (Figure 1) so as to achieve cooling of the movable contact 18 as wellas portions of stationary contacts 10 and 12, even though the contactsare engaged. I

While Figures 1, 4 and 5 have shown the pushrod as having a fluted topportion 36 to define air passages leading from the pushrod to theexternal area, it is clear that these passages could be formed in manydifferent ways. By way of example, Figures 2 and 3 show a secondembodiment of a pushrod head 38 which has a depression 40 therein whichis similar to depression 34 of Figures 1, 4 and 5. However, instead offluting the top of the pushrod head, a plurality of apertures such asapertures 42, 44, 4-6, 48, 50 and 52 are drilled from the side of thetop of the pushrod head and into the depression 40.

Accordingly, air or fluid from fluid conduit 22 may be directed into thecontacting area through the plurality of apertures 42 through 52 in amanner similar to that of Figures 1, 4 and 5.

Figure 6 shows the manner in which my novel aircooled contact may beapplied in a mechanical rectifier system. More specifically, in Figure 6an A.-C. source of voltage 54 is connected to the primary of a delta-Yconnected rectifier transformer which has a center tap brought out fromthe Y connected secondary to negative D.-C. terminal 56.

The other terminals of the Y connected secondary are then connected inseries with a first, second and third respective rectifier phase each ofwhich includes series connected commutating reactor 58 and contact 60. Acomplete description of the operation of commutating reactors, such asthe commutating reactor 58, is set forth in copendin application SerialNo. 301,880, now Patent No. 2,759,128, filed July 31, 1952 and assignedto the assignee of the instant invention.

Each of contacts 60 are of the type above described in conjunction withFigures 1, 4 and 5 and comprise stationary contacts 10 and 12 whichcooperate with a movable contact 18.

The movable contacts are, as previously described, moved out ofengagement with respect to their cooperating contacts 10 and 12 by meansof a pushrod 28, and the pushrods of the various phases are operated ina predetermined sequence by a linkage schematically indicated in Figure6 by a dotted line which is driven from the motor 30.

Each of the contacts 12 are then tied together and brought out to acommon positive terminal 62 whereby a D.-C. load is thereafterconnectable between terminals 56 and 62.

As has been previously described in Figures 1, 4 and 5, each of contacts60 has a fluid conduit 22 associated therewith. In Figure 6 I prefer toconnect each of conduits 22 to a common conduit 64 having one end 66closed and the other end connected to a compressor 68 or some similarsource of high pressure fiuid.

Accordingly, the compressor 68 will drive fluid through the main conduit64 and into the individual conduits 22 whereupon the air cooling andcleansing effect will be achieved in a manner described above for eachof the contacts.

Although I have described preferred embodiments of my novel invention,many variations and modifications will now be obvious to those skilledin the art, and I prefer therefore to be limited not by the specificdisclosure herein but only by the appended claims.

What is claimed is:

1. In a mechanical rectifier contact means comprising a movable contactmovable into and out of engagement with respect to a pair of relativelystationary contacts spaced apart from one another; said movable contacthaving biasing means asso'ciated therewith for biasing said movabledamned.

contact into bridging contact engagement with respect to said pair ofspaced stationary contacts; pushrod means engageable with the side ofsaid movable contact adjacent said stationary contacts for moving saidmovable contact against the force of said biasing means and to adisengaged position with respect to said stationary contacts; anaperture in said movable contact and a fluid conduit means extendingthrough said aperture and being directed toward said pushrod; saidpushrod being constructed to define a path for fluid flow from saidfluid conduit means to the area between said movable contact and each ofsaid pair of stationary contacts created when said movable contact ismoved to said disengaged position.

2. In a mechanical rectifier contact means comprising a movable contactmovable into and out of engagement with respect to a pair of relativelystationary contacts spaced apart from one another; said movable contacthaving biasing means associated therewith for biasing said movablecontact into bridging contact engagement with respect to said pair ofspaced stationary contacts; pushrod means engageable with the side ofsaid movable contact adjacent said stationary contacts for moving saidmovable contact against the force of said biasing means and to adisengaged position with respect to said stationary contacts; anaperture in said movable contact and a fluid conduit means extendingthrough said aperture and being directed toward said pushrod; saidpushrod being constructed to define a path for fluid flow from saidfluid conduit means to the area between said movable contact and each ofsaid pair of stationary contacts created when said movable contact ismoved to said disengaged position; said pushrod having a fluted headengaging said side of said movable contact to mechanically engage saidmovable contact in a non-airtight manner to thereby define said fluidflow path to said area.

3. In a mechanical rectifier contact means comprising a movable contactmovable into and out of engagement with respect to a pair of relativelystationary contacts spaced apart from one another; said movable contacthaving biasing means associated therewith for biasing said movablecontact into bridging contact engagement with respect to said pair ofspaced stationary contacts; pushrod means engageable with the side ofsaid movable contact adjacent said stationary contacts for moving saidmovable contact against the force of said biasing means and to adisengaged position with respect to said stationary contacts; anaperture in said movable contact and a fluid conduit means extendingthrough said aperture and being directed toward said pushrod; saidpushrod being constructed to deflect fluid flow from said fluid conduitmeans to an area between said movable contact and each of said pair ofstationary contacts created when said movable contact is moved to saiddisengaged position.

'4. In a mechanical rectifier contact means comprising a movable contactmovable into and out of engagement with respect to a pair of relativelystationary contacts spaced apart from one another; said movable contacthaving biasing means associated therewith for biasing said movablecontact into bridging contact engagement with respect to said pair ofspaced stationary contacts; pushrod means engageable with the side ofsaid movable contact adjacent said stationary contacts for moving saidmovable contact against the force of said biasing means and to adisengaged position with respect to said stationary contacts; anaperture in said movable contact and a fluid conduit means extendingthrough said aperture and being directed toward said pushrod; saidpushrod being constructed to define a path for fluid flow from saidfluid conduit means to the area between said movable contact and each ofsaid pair of stationary contacts created when said movable contact ismoved to said disengaged position; said fluid flow to said area coolingeach of said stationary contacts and said movable contact and dislodgingforeign particles from said area.

5. In a mechanical rectifier contact means comprising a movable contactmovable into and out of engagement with respect to a pair of relativelystationary contacts spaced apart from one another; said movable contacthaving biasing means associated therewith for biasing said movablecontact into bridging contact engagement with respect to said pair ofspaced stationary contacts; pushrod means repetitively engageable withthe side of said movable contact adjacent said stationary contacts formoving said movable contact against the force of said biasing means andto a disengaged position with respect to said stationary contacts; anaperture in said movable contact and a fluid conduit means extendingthrough said aperture and being terminated in a depression in saidpushrod in a position substantially aligned with the area createdbetween said movable and stationary contacts when said movable contactis moved to said disengaged position; said pushrod having a fluted headengaging sa d side of said movable contact to mechanically engage saidmovable contact in a non-airtight manner to thereby define said fluidflow path to said area.

6. A contact device comprising a relatively stationary contact and acooperating movable contact movable between a contact engaged positionand contact disengaged position with respect to said relativelystationary contact; a pushrod means operatively connectable to saidmovable contact for moving said movable contact to at least one saidcontact engaged or contact disengaged positions; an aperture in saidmovable contact and a fluid conduit means extending through saidaperture and having an open end terminated in a depression in the end ofsaid pushrod operatively connected to said movable contact; said pushrodmeans having a fluid passage therein for directing fluid received bysaid depression in said pushrod end from said fluid conduit means to thearea created between said movable and stationary contacts when saidmovable contact is moved to said contact disengaged position.

7. A contact device comprising a relatively stationary contact and acooperating movable contact movable between a contact engaged positionand contact disengaged position with respect to said relativelystationary contact; a pushrod means operatively connectable to saidmovable contact for moving said movable contact to at least one of saidcontact engaged or contact disengaged positions; an aperture in saidmovable contact and a fluid conduit means extending through saidaperture and having an open end terminated in a depression in the end ofsaid pushrod operatively connected to said movable contact; said pushrodmeans having a fluid passage therein for directing fluid received bysaid depression in said pushrod end from said fluid conduit means to thearea created between said movable and stationary contacts when saidmovable contact is moved to said contact disengaged position; saidpushrod end having a fluted head engaging the side of said movablecontact engageable with said stationary contact to mechanically engagesaid movable contact in a non-airtight manner to thereby form said fluidpassage; said fluid flow to said area cooling each of said stationaryand movable contacts and dislodging foreign particles from said area.

References Cited in the file of this patent UNITED STATES PATENTS1,612,318 Riley Dec. 28, 1926 2,039,838 Sandicoeur May 5, 1936 2,072,112King Mar. 2, 1937 2,634,341 Rosen Apr. 7, 1953 2,741,735 Wasserrab Apr.10, 1956 2,863,112 Kleinvogel Dec. 2, 1958 FOREIGN PATENTS 897,409France May 22, 1944 615,727 Germany Apr. 19, 1956

